In recent years, monitor cameras with rotationally movable mechanisms have been widely used for the purposes of security or monitoring of production lines.
In the case of surveillance monitors, for example, high definition surveillance monitors such as Hi-Vision (HV) cameras are often used as surveillance monitors. In such monitor cameras, a two-way digital transmission function would be essential for capture-tracking control information of a subject to be photographed, photographing information of a camera, etc.
Furthermore, policies for obliging safety when driving a car by transferring the change in air pressure and temperature of a car tire to the main body of the car have been implemented in the United States and other countries. In such a case, a two-way transmission function is needed. In addition, the realization of means for rapidly transmitting information obtained at the head part to the body part of a robot and a high-speed digital link between objects that rotate with respect to each other is requested.
As described above, in recent years, the need for a digital link between rotating objects has been rapidly increasing.
However, since a line transmission method such as an electric wire may cause a cut or a remarkable reduction in reliability when it is applied to a rotationally movable mechanism, there is a need for the development of rotationally movable mechanisms to which a radio transmission method is applied.
An example of a rotationally movable mechanism of a radio transmission method may include a rotary optical link joint disclosed in, for example, patent document 1. The rotary optical link joint disclosed in patent document 1 is characterized in that a bundle fiber that is bundled from a plurality of single-core optical fibers is relatively rotatably maintained centered around an axis line.